Herein, acrylates and methacrylates are collectively referred to as (meth)acrylates. (Meth)acryloyl group is a similar reference.
Water and oil proofings containing a fluorocopolymer comprising polymerized units based on an Rf group-containing monomer which forms a homopolymer having a melting point attributable to crystallites of polyfluoroalkyl groups (hereinafter referred to as Rf groups) (hereinafter also referred to as an Rf group-containing crystalline polymer) have been proposed.
As the fluorocopolymer, a quaternary fluorocopolymer comprising polymerized units based on an acrylate having a perfluoroalkyl group (hereinafter referred to as an RF group), polymerized units based on stearyl (meth)acrylate, polymerized units based on 2-chloroethyl vinyl ether and polymerized units based on N-methylol(meth)acrylamide (Patent Document 1), a quaternary fluorocopolymer comprising polymerized units based on an acrylate having an RF group, polymerized units based on a (meth)acrylate having an alkyl group or the like, polymerized units based on an acrylate having a polyoxyalkylene group and polymerized units based on an acrylate having a dialkylamino group (Patent Document 2) or a quaternary fluorocopolymer comprising polymerized units based on a (meth)acrylate having an RF group, polymerized units based on a (meth)acrylate having an alkylamino group, polymerized units based on a vinyl carboxylate or an alkyl vinyl ether and polymerized units based on another monomer other than the aforementioned three (Patent Document 3) may be mentioned.
However, most of them use RF group-containing (meth)acrylates having a carbon number of 8 or above. RF group-containing (meth)acrylates having a carbon number of from 1 to 6 have not been industrially utilized fully.    Patent Document 1: JP-A-10-237133    Patent Document 2: JP-A-5-271351    Patent Document 3: JP-A-7-206942